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Bone Response to Damage (view source)

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<big><center>[[Bones|'''BACK TO BONES''']]</center></big>

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~~ INTRODUCTION~~

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Bone is a hard, highly specialised connective tissue comprising interconnected cells embedded in a calcified, collagenous matrix. It is a living, dynamic, responsive tissue, growing and remodelling throughout life. The pathogenesis of many bone diseases is complex and may involve genetic defects, diet or infection (or, horror of horrors, a combination of these).

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~~A FEW REMINDERS………~~

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===Introduction===

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~~I. NORMAL FUNCTION AND STRUCTURE~~

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Function: Support/protection~~, movement, stem~~ cell storage~~, mineral~~ storage

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*Bone is a hard, highly specialised connective tissue

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~~Structure: Bone is composed of cells and matrix~~

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*Consists of interconnected cells embedded in a calcified, collagenous matrix

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*Living, dynamic, responsive tissue, growing and remodelling throughout life

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*Pathogenesis of many bone diseases is complex

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**May involve genetic defects, diet or infection or a combination of these

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*'''Function''':

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**Support/protection

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**Movement

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**Stem cell storage

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**Mineral storage

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~~Cells: 1. Osteoblasts~~

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~~2. Osteocytes~~

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~~3. Osteoclasts~~

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~~Osteoblasts~~

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===Normal structure===

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~~• Mesenchymal cells which arise from bone marrow stroma~~

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~~• Produce bone matrix~~ = ~~osteoid~~

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~~• Cell membranes are rich in alkaline phosphatase (ALP)~~

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~~Osteocytes~~

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*'''Cells'''

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• Osteoblasts ~~that have become surrounded by mineralised~~ bone matrix

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**'''Osteoblasts'''

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~~• Occupy cavities called lacunae~~

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***Mesenchymal cells

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***Arise from bone marrow stroma

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***Produce bone matrix = '''osteoid'''

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***Cell membranes are rich in alkaline phosphatase (ALP)

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~~Osteoclasts~~

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**'''Osteocytes'''

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~~• Multinucleated cells derived from haematopoietic stem cells~~

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***Osteoblasts that have become surrounded by mineralised bone matrix

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~~• Responsible for bone resorption (have a brush border for this)~~

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***Occupy cavities called '''lacunae'''

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~~Matrix~~

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**'''Osteoclasts'''

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~~• Type I collagen forms the backbone of the matrix~~

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***Multinucleated cells

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~~• Mineral – accounts~~ for ~~65% of~~ bone ~~and includes Ca, P, Mg, Mn, Zn, Cu, Na~~

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***Derived from haematopoietic stem cells

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***Responsible for bone resorption (have a brush border for this)

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Bone organisation

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*'''Matrix'''

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**Type I collagen forms the backbone of the matrix

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**Mineral – accounts for 65% of bone and includes Ca, P, Mg, Mn, Zn, Cu, Na

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===Bone organisation===

Osteoblasts deposit collagen in different patterns

Bara

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